My guess is that, even though Ваня is the friendly informal form of Иван, they are not universally interchangeable. Using Ваня in a formal context would be unacceptable for example. So if the sentences uses the informal nickname Ваня, it is better to keep it so in the translation.
Firstly, that's cool that Vanya is also in Portuguese. Second, no, both aren't male names. Vanya is female, and Ivan is a common male, exactly like in Portuguese.
Edit: Sorry!! I just looked up and saw that Vanya is just a different word for Ivan. Vanya is a kind of nickname for Ivan, I think. Please correct me, please! You use it when you know someone well enough to use "ты".
As accepted as it would be if having met someone called Charles, you called him Charlie.
I'd recommend reading the Wikipedia page about it: https://en.wikipedia.org/wiki/List_of_diminutives_by_language#Russian
Long story short, diminutives are often used to denote the smallness of something (книга - book; книжка - little book) or to demonstrate endearment or intimacy with someone (like calling your friend Ваня instead of Иван).
Yes, and we put a dash ("—", тире) in other cases. Russians often confuse these difficult rules too. After personal pronoun we don't put a dash usually. Compare: "Дом — здание." (A house is a building.), "Он ребёнок." (He is a child.). We don't use a dash before negation: "Дом не дерево." (A house is not a tree.)
Do not confuse a dash ("—", тире) with a hyphen ("-", дефис) which connect words parts. It is possible to use short sign in both cases, but a dash must be between spaces.
thanks, may be I am confused with the way that Russian grammar works, the sentences have a different structure from my language or English. I wish duolingo would provide some grammar rules too as I am going through lessons but at times I do not understand why it is used a certain form of a word or why they do not accept privet for hello at some cases, but sdrasvujte. It does not explain which is formal or non formal as in English is simple: Hello. Anyway, still I have learned quite a lot in just a month.
If it's a person's name or initials, it will always be capitalized.
For names of organizations, agencies, institutions, only the first word will be capitalized (unless it's named after someone, then that person's name will also be capitalized). For instance: МГУ - Московский государственный университет.
If it's a name of a place, the actual name of the place is capitalized but the type of place is not. For instance, in English we would write "Leningrad Street", but in Russian they would write "ул. Ленинградская".
Why did it correct me for writing the name in Russian? Surely you wouldn't write someones name out in a different language just because you spoke in that language with them? Especially if neither of you are speaking your native tounge. It'd be amusing to translate my name into Russian as there's not the sound for it!
Transliteration (the act of writing out the characters by sound from one language into another one) is different from Translation, which is the act of changing the words from the source material into comparable words so that the meaning remains the same in the target language. You're correct that you would not translate the foreign name, but in order for this sentence to make sense in English, you will have to transliterate the name, so that a non-Russian speaker/reader can understand the sentence completely. "Hello, I am Ваня" does me no good if I do not know the Cyrillic alphabet, because I do not know how Ваня is to be pronounced. By transliterating it to Vanya, I have a much clearer idea of what the name is.
Likewise, from a learning perspective, the program can't tell if you know how the name is supposed to be spelled/pronounced in English if you type it in Cyrillic.